1978 75HP Johnson problems

[PISTONESAL]

Hello,

I have a boat I got from my dad with a 1978 75HP outboard motor (75ELR78C). He said it runs. It starts up real good and idle good for the most part. I got it in the water and it ran good and it got real good high speed, but all of a sudden it slowed down and would not go to higher speed and I had the throttle maxed out. It did run good again and then the same thing. I replaced a cracked fuel hose assuming that would fix the problem. But it didn't, it just does not want to get up to fast speed. At the end of the day going to the dock, it could no longer start. The started gear would spin but not go upto the flywheel. I tried a lot of times and nothing. The next day I turned the gear upto the flywheel by hand and now the engine starts. I sprayed some WD40 on it. I don't know if it got stuck or what. Can you shed some light? I would really appreciate it.

I cleaned the carbs, they look in great shape. I replaced all the hosing and cleaned the fuel filter. Next weekend, I put the boat out on the water and it started just fine. I was going out and it suddenly died. I try to start it and it would turn but not start. After trying a few times, I noticed that the gear shifter was stuck. i moved it by hand and the engine started but I could not go into forward or reverse. It would cutoff everytime. It will stay in neutral and it actually brought me back to the dock. I stayed at the dock and tryed to get it going and it would start but I could not engage to go forward or reverse becaue I soon as I would, it would cutoff. I took it out 2 weeks later and now it just won't start. It turns over but won't start. This is where I am with it now. Any suggestions? Please let me know.



Thanks

Sal

 

[HighTrim]

Re: 1978 75HP Johnson problems

You are going to have to perform a few tests before continuing.

First check the compression. Your readings should be around 100 psi, and even, or within 10 percent, on all cylinders.

Then check the spark. You should get a strong blue ZAP!! and the spark should jump a 7/16 of an inch gap on the inline tester.

If those both check out, you probably have a fuel delivery issue. Was the carb thoroughally cleaned? All orifices and jets blown out with compressed air and cleaned?

Do you have a built in tank or portable?

Regarding the starter not engaging the flywheel, you probably either have a faulty or undercharged battery or a wiring/connection issue. Check to ensure your battery is fully charged (12.65 VOlts) and load tested. Then go over all connections, polishing them with sandpaper or a file and make them SHINE! Then check all wiring from the battery, solenoid, starter and inspect for nicks, abrasions, cuts, or crunching when you flex it. That is a sure sign of inner corrosion.

 

[tashasdaddy]

Re: 1978 75HP Johnson problems

how long did this motor sit without being run when you got it. if you have spark and equal compression sounds like you need to throughly soak the carbs, remove the high and low speed jets, with the special tool 317002 or make one, below. then you need to set your idle speed IN THE WATER, AND IN GEAR, not on muffs at home.

 

[PISTONESAL]

Re: 1978 75HP Johnson problems

High trim,

Thanks for the reply. I had good compression on all 3 around 130. I had spark on all 3. i have a portable 6 gallon tank. I replaced all lines, fuel, and fuel pump on the tank. I cleaned the carbs. Last night I soaked them for 30 minutes. Today or tomorrow I will finish installing and try again. I have the battery full charged. I put a jump box on it also thinking it might have been the battery. started does engage, it just doesn't always go back down. Sometime it does and sometimes it doesn't. I spray some Wd40 and its OK. I checked and cleaned all wires and connections. If all above fails, I was going to replace the coils and if that doesn't work I was just going to bring it to a mechanic. I am leaving for 2 weeks so I thought I would leave it with him so it would be complete by then. It will give him time if he needs to order parts. Unless you have any suggestions.


Tashasdddy,

Thanks for the reply see above. I don't know how long it sat. All I know is that it would start great when I first tryed it. Any other suggestions? If you can call I will be working on this boat all day Saturday before my 2 week bussinnes trip. I apppreciate all replys..

thanks

Sal

 

[HighTrim]

Re: 1978 75HP Johnson problems

What is the condition of the bendix and the teeth? Short of it being damaged, the condition you are referring to is usually due to a faulty battery or wiring/connection issues. A voltage drop test will verify this.

Also forget the wd 40, use a light weight oil like sewing machine oil, or I use 3 in 1, at the appropriate lube areas.

 

[PISTONESAL]

Re: 1978 75HP Johnson problems

Hey everybody,

Unbelievable. After doing what I said, soaking the carbs and putting RTV on all the gaskets and putting them back together and back on the boat vola, it works. After a few trys, the engine started. I would shut it off, and would turn on immediately when I turned the key. took it to the lake and it ran great. It even got to top RPM. It was excellent. Only one little issue. Sometimes it engages to go forward and sometimes it doesnt. It will engage all the time in reverse but not always in forward. Any suggestions? Please advise.

Thanks

 

[wavrider]

Re: 1978 75HP Johnson problems

Could possibly need linkage adjusted,
Try disconnecting the shift cable and shift by hand, if it goes into gear easy and every time then you know it is cable or remote control related.

Sometimes the cable can get lose at the connection and cause some play in the shift cable.

 

[PISTONESAL]

Re: 1978 75HP Johnson problems

Which side? The motor side or the control side? Can you also be ore specific?

Thanks

Sal